Alternate Names : Magnetic Resonance Imaging, Nuclear Magnetic Resonance (NMR) Imaging

Definition

MRI is a non-invasive procedure that uses powerful magnets and radio waves to construct pictures of the body.

Unlike conventional radiography and Computed Tomographic (CT) imaging, which make use of potentially harmful radiation (X-rays), MRI imaging is based on the magnetic properties of atoms. A powerful magnet generates a magnetic field roughly 10,000 times stronger than the natural background magnetism from the earth. A very small percentage of hydrogen atoms within a human body will align with this field.

When focused radio wave pulses are broadcast towards the aligned hydrogen atoms in tissues of interest, they will return a signal. The subtle differences in that signal from various body tissues enables MRI to differentiate organs, and potentially contrast benign and malignant tissue.

Any imaging plane (or "slice") can be projected, stored in a computer, or printed on film. MRI can easily be performed through clothing and bones. However, certain types of metal in the area of interest can cause significant errors in the reconstructed images.